(1) Field of the Invention
The present invention relates to a tool unit applied to ultrasonic machining, particular to one that is suitable for ultrasonic machining in micron precision to workpieces made of brittle materials.
(2) Description of the Prior Art
Normally, ultrasonic machining process is used to cut brittle materials. The operation of the ultrasonic machining process is essentially performed by a vibrating tool unit disposed at the front of the ultrasonic machining apparatus, wherein the vibrating tool unit is resonated to oscillate at ultrasonic frequencies produced by an ultrasonic generator.
Following the progressive trend for the science and technology, the miniaturizing requirement of the industrial product becomes inevitable. However, two impending issues in most conventional ultrasonic machining apparatus are urgently needing be solved. Firstly, in a common assembly of the conventional ultrasonic machining apparatus, the machining head of cutting tool is rigidly connected to the ultrasonic amplitude transformer by means of fasteners such as screws or metal buckling rings, which unavoidably creates somewhat irregular gaps scatter along the connecting section between the machining head of cutting tool and ultrasonic amplitude transformer. Accordingly, the machining precision is worsened due to uneven distributions of the vibration amplitude over the machining head of cutting tool so that the machining precision can not be improved up to micron scale still being kept at millimeter scale.
Secondly, the machining head of cutting tool in common assembly of the conventional ultrasonic machining apparatus is made of materials selected from metals or metal alloys, which are always confined to short service life due to susceptible to quickly wearing and damage under the ultrasonic vibration. A common preliminary solution to improve the service life for the machining head of cutting tool is that coating a layer containing diamond or diamond-like materials over the substrate of the cutting tool via plasma-enhanced deposition technique. However, this preliminary solution did not thoroughly solve the drawbacks of the cutting tool because the problematic issue in the connecting section between the machining head of cutting tool and ultrasonic amplitude transformer is still not solved yet. Having realized and addressed foregoing issues, the present invention is worked out to thoroughly solve them without sacrificing the precision level even under harsh machining condition for a long time.